The present invention relates to a zoom lens and, in particular, relates to one such zoom lens having a high speed multi-lens drive.
Conventional zoom lenses typically include stepper or DC motors with a rotary optical encoder and lead screw combination dedicated to each individual lens drive, i.e., each zoom lens and each focusing lens. The resolution of this system is set by the combination of the number of steps produced in one revolution and the pitch of the lead screw. In addition, the high resolution requirement tends to limit the speed. In such a system the resolution is limited, as well as being difficult to miniaturize due to the multi-motor arrangement. Consequently, it is highly desirable to provide a zoom lens that substantially overcomes the above-recited disadvantages of the conventional zoom lenses.